Cross-browser compatibility of HTML5 games: test matrix

1) Why HTML5 games "hurt" cross-browsing

Games affect almost all layers of the platform: graphics (Canvas/WebGL/WebGPU), timers and streams (RAF/Workers), sound (WebAudio/Media policies), input (keyboard/pointer/touch/gamepad), network and caches (SW/Cache/Indepad exedDB), integration (fullscreen/orientation/PWA). Different engines - Chromium (Chrome/Edge/Opera/Android), WebKit (Safari/macOS, iOS/iPadOS in all browsers), Gecko (Firefox). Plus differences in power saving, throttling background tabs, memory limits and autoplay policies.

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2) Supported environments: target matrix

Browsers/OS (minimum versions are an example, substitute your SLAs):

• Desktop: Chrome/Edge 116+, Firefox 115+, Safari 16+ (macOS 12+).
• Mobile: Chrome Android 116+ (Android 9+), Samsung Internet 21+, Safari iOS/iPadOS 16+.
• WebView: Android WebView 116 +, iOS - only WebKit (all browsers on iOS use WebKit).
• PWA (installation): Chromium desktop/mobile, Safari iOS 16. 4 + (Add to Home Screen with restrictions).

Hardware classes:

• Low (mobile budget, 2 GB RAM)
• Medium (mobile/ultrabooks, 4-8 GB RAM)
• High (desktop/consumer GPU, 8-16 + GB)

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3) Large test matrix (template)

Form a real table in your tracker. Below are the key blocks and statuses (OK/Partial/N/A) that need to be measured.

3. 1 Graphics

3. 2 Audio and Media Policies

3. 3 Input and interface

3. 4 Performance and energy saving

3. 5 Saves/offline/network

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4) Minimum set of manual scripts (Smoke)

1. First start: loading assets, splash, level start <3 s on the middle class.

2. Input: touch/mouse/keyboard/gamepad, multiple fingers, hold, swipes.

3. Screen: full screen, orientation lock, safe-area (iPhone with bangs).

4. Audio: first note after custom gesture, mute/unmute, music mix/FX.

5. WebGL: loss/recovery of context (simulate), shadows/shaders/scale.

6. Life cycle: collapse/expand, call/notification, tab in the background.

7. Saves: progress/settings in IndexedDB/LocalStorage, recovery after restart/offline.

8. Network: 3G throttle/high RTT, network loss, retray, caching via SW.

9. PWA: installation (Chromium/iOS), icons, offline page, version update.

10. Long session: 20-30 minutes without leaks (FPS/heap stable).

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5) Automation: how and how

Playwright (recommended): cross-engine, mobile emulations, WebKit driver, video/tracks.

Cypress: fast dev loop, but WebKit/mobile is limited.

WebDriver/Selenium: cloud integration.

Clouds: BrowserStack, Sauce Labs - real devices and iOS Safari.

Profiling: Chrome DevTools Protocol, Safari Web Inspector (Remote), Firefox Profiler.

Perf scripts: k6/browser for RUM-like asset loading scripts.

Tip: keep a "package" of autotests for 3-5 minutes (smoke) for each PR: loading, one game cycle, pause, switching orientation, checking save.

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6) Performance: target metrics and telemetry

FPS: stable 60 fps (or 120 on ProMotion) - capture frame pacing, not just the average.

Frame budget: 16. 7 ms (or 8. 3 ms) on update + render, GC <2-3 ms per frame.

Input latency: <80 ms mobile, 50 ms desktop

Time-to-First-Frame (TTFF): < 1. 5 s (after loading assets).

Heap growth: no more than + 10% per 20 minutes of session; lack of runaway allocations.

Audio latency: <100ms roundtrip.

Embed RUM: send FPS, TTFF, heap, WebGL context lost telemetry, rendering errors by 'browser/os/device'.

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7) Frequent incompatibilities and how to treat

7. 1 Graphics/render

HiDPI Canvas-Set logical size = CSS px, physical = 'css devicePixelRatio'.

WebGL context lost: listen to 'webglcontextlost/webglcontextrestored', store resources for reboot.

Textures/shaders: avoid non-universal extensions; check OES _ texture _ float, EXT _ color _ buffer _ float, and fallback.

WebGPU: roll feature-flag; keep WebGL2 path as a fallback.

7. 2 Audio/autoplay

Start AudioContext with a custom gesture ('tap/click') and keep the "allowed" flag.

On iOS, prepare to suspend when minimizing/switching.

7. 3 Input/gestures

Listeners of events make passive by default; where'preventDefault () 'is to explicitly disable passive.

Pointer Events + Touch Events - avoid double processing; abstract the input layer.

Gamepad: check 'navigator. getGamepads () 'via RAF, take into account the layout of the buttons.

7. 4 Fullscreen/Orientation/Safe-Area

For iOS, consider 'env (safe-area-inset-)', add padding to the canvas/Overlay UI.

Orientation lock only after user gesture; have a "rotate screen" button.

7. 5 Storigi/Offline

IndexedDB: wrap operations in timeouts/retrays; on iOS, quotas are small - keep lightweight saves.

Service Worker: 'Stale-While-Revalidate' strategy for assets; honestly disabled versions (content-hash).

LocalStorage may not be available in private modes - degrade to warning memory.

7. 6 Timers/background

In the background, timers clump up to 1 s or more. Stop the heavy logic, pause the game.

Enable page visibility/' visibilitychange 'and event-driven updates instead of intervals.

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8) Pipeline assembly for crossbrowser

Transpilation: TypeScript/Babel targets' es2020 '(or lower for older WebViews).

Polyphylls: feature detection only, not UA.

Assets: sprite sheets, textures with fallback formats (WebP/PNG), audio (AAC/OGG/Opus).

Code separation: lazy-chunks for editor/non-game panels.

Compression: Brotli/Zstd; HTTP/2/3; CDN with immutable-versioning.

Feature flags: WebGPU/OffscreenCanvas/Threads - enable by whitelist.

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9) Checklist templates

9. 1 Smartphone (Android/Chrome, iPhone/Safari)

• Touch + multi-touch; gestures do not "pull" the page
• Fullscreen and orientation; safe-area correct
• First sound after tap; mute works
• FPS ≥ 50 (low class), no ragged frame
• Save/Restore progress after restart
• Offline scene/SW restart
• System overlay call (incoming call) → correct pause

9. 2 Desktop (Windows/macOS)

• Mouse + wheel + keyboard, IME
• Gamepad (XInput/Generic)
• 60/120Hz monitors: stable frame pacing
• Alt-Tab/multiple monitors/fullscreen/windowed
• Memory

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10) Code examples (fragments)

Canvas с HiDPI:

js function resizeCanvas(canvas) {
const dpr = Math. min(window. devicePixelRatio          1, 2);
const { clientWidth:w, clientHeight:h } = canvas;
canvas. width = Math. floor(w dpr);
canvas. height = Math. floor(h dpr);
const ctx = canvas. getContext('2d');
ctx. setTransform(dpr, 0, 0, dpr, 0, 0);
}

WebGL: context loss handling:

js const gl = canvas. getContext('webgl', { preserveDrawingBuffer:false });
canvas. addEventListener('webglcontextlost', e => { e. preventDefault(); paused = true; });
canvas. addEventListener('webglcontextrestored', () => { reloadResources(); paused = false; });

Audio "unlock":

js let audioUnlocked = false;
window. addEventListener('pointerdown', () => {
if (!audioUnlocked) {
const ctx = new AudioContext();
const b = ctx. createBuffer(1, 1, 22050);
const s = ctx. createBufferSource();
s. buffer = b; s. connect(ctx. destination); s. start(0);
audioUnlocked = true;
}
}, { once:true, passive:true });

Page Visibility:

js document. addEventListener('visibilitychange', () => {
if (document. hidden) pauseGame();
else resumeGame();
});

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11) Risk management and prioritization

Murphy's Law for iOS: Test every minor version of iOS from your matrix - regressions are frequent.

WebView OEM: Android devices with outdated WebView are a separate risk layer (enter "greylist" devices).

Functional flags: include problem features by brand/market-pilots.

Rollout: 1% → 10% → 50% → 100% with RUM gates (FPS, crash, TTFF).

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12) Observability and bug reports

Include in each bug report: 'ua', 'browser version', 'os', 'device', 'gpu/renderer', 'memory', 'fps', 'logs (WebGL/WebAudio errors)', 'steps', 'repro video'.

Automatic sending of crash dumps (JS errors/resources), 'context lost', 'audio unlock failed' events.

Dashboards: FPS by browser/device, average TTFF, context lost share, IndexedDB errors, SW offline hits.

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13) Final template matrix (CSV fish)

Platform,Browser,Version,Feature,Scenario,Expected,Status,Notes
Android,Chrome,116+,WebGL2,Context lost/restore,State restored,OK, iOS,Safari,16. 6,Audio,First sound on tap,Plays,PARTIAL,Silent switch affects
Desktop,Firefox,115+,Fullscreen,Enter/Exit,No layout jump,OK, Android,WebView,116+,Storage,IndexedDB quota,Save 5MB,PARTIAL,Quota lower on device X iOS,Safari,16. 4+,PWA,Install & relaunch,State persisted,OK, ```

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14) Production readiness checklist

[] Fixed browser/version/device matrix and SLA update.
[] Smoke-set of autotests (Playwright) is launched on PR and nightly; reports with video/tracks.
[] RUM telemetry FPS/TTFF/heap/WebGL errors with browser/device section.
[] Folbeki: WebGL1 ← WebGL2 ← WebGPU; Audio unlock; Pointer/Touch abstraction.
[] Processed lifecycle/visibility, pause/resume, offline, context lost.
[] Persistence is stable (IndexedDB + degradation), asset version immutable via SW/CDN.
[] Profiles on real devices (iOS/Android) and 60/120 Hz desktops.
[] Documentation of known restrictions (iOS autoplays, IDB quotas, orientation).
[] Rollback plans/feature-flags for problematic features (WebGPU/Threads).
[] Feedback channel in the game (feedback + log dump).

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Resume Summary

Cross-browser compatibility of HTML5 games is not one check box "works in Safari," but a discipline: a rigid platform matrix, measurable metrics (FPS/TTFF/heap), autotests on real devices, folkbacks of graphics/audio/input and careful work with offline and saves. Enter a stable testing pipeline, collect RUM and keep the features behind the flags - this way the game will be equally smooth and predictable on Chrome, Safari and Firefox, on your phone and desktop.